burnt pistons

[swrracing99]

I have had this problem for the last 3 times I have built my motor. I have been running E-85 just wondering if anyone else has had this problem. The crazy this is it burnt the back 2 cylinders on each side really bad. I have been told timing issue, lean, too rich or vacuum leak. I do know that I am tired of building motors only to burn pistons. The last 3 motors have only lasted not even 2 races. Any suggestions would be appreciated. QFT 500 2bbl, vortec heads, 34 deg timing, 92 jets, 7 1/2 lbs of fuel pressure, holley aftermarket pump.

[ford396]

Not sure about the burnt pistons, but 34 degrees of timing seems like to much for vortec heads. I have always been 30 - 32 degrees. ??

[Drake Racing]

what intake are u using? When using an adjustable carb adapter we used to have problems leaning out back cylinders with the Torker intake. Solution was move adapter all the way back for more fuel back there.

Curt Drake
Stock Car #55x

[fast_crew]

Vortecs generaly don't like more then 32*. What power valve you running, maybe too low and closing to soon on the top end and leaning out. What size jets came in carb? Not sure on jetting as Ive never ran E-85, what does the carb builder say. Are the headers leaking at all? Just a few thoughts.

[swrracing99]

I run a edelbrock rpm airgap. The carb came with 86 jets in it new. But after burning pistons and it looking lean we kept going up. No sign of an exhaust leak. I am not sure of power valve but i think it is a 4.5 or 5.5.

[fast_crew]

Where are the pistons burning and what brand and type?

[rcstreet1]

I dont no much about e85 but 92 jets sound lean. I run 87s with race gas. Do all ur plugz look lean or just the cylinders with burnt pistons.

[swrracing99]

They are Keith Black silvo-lite hyper pistons. 2 pistons have holes in the center the size of half dollars, 1 is burnt all the way down the side to the wrist pin and the other one looks like a wood pecker got ahold of it plus the top ring land is burnt completely off. You could see all 3 rings will it was still in the block. I have 2 other friends that run E-85 with different brand carbs and both of theres have 86 jets as well. Im not sure what the deal may be.

[fast_crew]

Are you clearancing the top ring gap per K/B's specs? This could explain the ring land issues but probably not the ones burnt through the middle What spark plug are you running, too hot maybe? When did this problem start? With the use of the E-85 im presumming? What size fuel line are you running? Check for kinks or restrictions, clogged fuel filter (using a stainless element I hope)

[twisterf5]

what size is the engine we run E-85 from crates to supers and just ran last night in our steel head. never any problems but we do dyno most of our stuff. a 500 2b is bigger than a 750 4b. on the front side we build our own carbs. we run a 7.5 power valve with the holes behind it drilled out to 1/16 that is a must. our 750 carb on a 700hp steel head is jetted at 97 front 99 rear on two power valves. depending on engine size you are way lean.and would think you need to be near the 100 mark and if the holes are not drilled out they need to be. you use 30% more fuel so the holes and jets need to be at least 30% bigger. hope this helps

and for best results to get rid of that stumble that people talk about use a 50cc pump a 47 squirtter and a holly yellow cam and you will never have any problems.

[50j]

I have had this problem for the last 3 times I have built my motor. I have been running E-85 just wondering if anyone else has had this problem. The crazy this is it burnt the back 2 cylinders on each side really bad. I have been told timing issue, lean, too rich or vacuum leak. I do know that I am tired of building motors only to burn pistons. The last 3 motors have only lasted not even 2 races. Any suggestions would be appreciated. QFT 500 2bbl, vortec heads, 34 deg timing, 92 jets, 7 1/2 lbs of fuel pressure, holley aftermarket pump.

Check your pm.

[50j]

what size is the engine we run E-85 from crates to supers and just ran last night in our steel head. never any problems but we do dyno most of our stuff. a 500 2b is bigger than a 750 4b. on the front side we build our own carbs. we run a 7.5 power valve with the holes behind it drilled out to 1/16 that is a must. our 750 carb on a 700hp steel head is jetted at 97 front 99 rear on two power valves. depending on engine size you are way lean.and would think you need to be near the 100 mark and if the holes are not drilled out they need to be. you use 30% more fuel so the holes and jets need to be at least 30% bigger. hope this helps

and for best results to get rid of that stumble that people talk about use a 50cc pump a 47 squirtter and a holly yellow cam and you will never have any problems.

Probably good intentions but completely wrong.

[twisterf5]

Probably good intentions but completely wrong.

well what is what we run. and with 287 wins 9 championships mostly on menthanol in owm and with E-85 in the large tire cars we run.think im going to stick with it.

[50j]

If it works for you, great, but running "menthanol" has nothing to do with E-85 and the jet size you suggested would never run. A 500 is half a 750. He can try it but it'll spit and sputter so bad he won't even run 2 laps like that.

[twisterf5]

If it works for you, great, but running "menthanol" has nothing to do with E-85 and the jet size you suggested would never run. A 500 is half a 750. He can try it but it'll spit and sputter so bad he won't even run 2 laps like that.

yes you are right it is not menthanol but i said we are on E85 and have been for the last 4 years.
crate 86/88
built motor 700 hp 97/99
dyno at a 9-1 air fuel
timing in all 3 crates we run 36
open built motor 39
so i know it is not his timing and if he has 93 jet now one would think it is still lean.
just because i can he can send me the carb i will fix it and dyno it on a 600hp engine for free.

and i would rather have one spit and sputter and have to jet it down than run one lean and burn it to the ground.